BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)					3 Months Ended		4 Months Ended	9 Months Ended
	Sep. 14, 2020 USD ($) shares	Jun. 30, 2020 shares	Jun. 09, 2020 USD ($) shares	Apr. 25, 2019	Dec. 05, 2020 USD ($) store_format shares	Nov. 30, 2019 USD ($)	Jun. 20, 2020 USD ($)	Dec. 05, 2020 USD ($) division store_format segment shares	Nov. 30, 2019 USD ($)	Oct. 14, 2020 USD ($)	Feb. 29, 2020 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash					$ 50,600,000			$ 50,600,000			$ 8,200,000
LIFO expense					14,300,000	$ 2,600,000		37,500,000	$ 18,900,000
Equity-based compensation expense					1,500,000	900,000		4,000,000.0	3,000,000.0
Repurchase of common stock			$ 1,680,000,000.0					1,864,700,000	0
Income tax expense					$ 29,500,000	$ 12,900,000		$ 342,600,000	$ 110,500,000
Effective tax rate					19.30%	19.10%		25.60%	21.70%
Number of divisions | division								12
Number of reportable segments | segment								1
Number of store format | store_format					1			1
Receivables, net					$ 549,500,000			$ 549,500,000			525,300,000
Contract liability related to gift cards					91,600,000			91,600,000			52,200,000
Deferred employer paid portion of social security taxes								396,000,000
Stock repurchased					184,700,000		$ 1,680,000,000.0
Pharmacy
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, net					245,600,000			245,600,000			$ 218,500,000
Common Stock
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of shares repurchased (in shares) | shares			101,611,736
Stock Repurchase Program, Authorized Amount										$ 300,000,000
Class A Common Stock
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Repurchase of common stock					$ 102,700,000
Repurchase of common stock (in shares) | shares	6,837,970				6,797,962
Stock repurchased	$ 82,000,000.0
Phantom Units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Awards converted (in shares) | shares			11,300,000
Equity-based compensation expense					$ 13,600,000	$ 6,300,000		39,400,000	$ 21,800,000
Income tax benefit					3,500,000	$ 1,600,000		10,100,000	$ 5,700,000
Compensation cost not yet recognized					$ 98,000,000.0			$ 98,000,000.0
Number of unvested phantom units (in shares) | shares					8,700,000			8,700,000
Period for recognition of unrecognized compensation cost								2 years
Phantom Units | Investor Incentive Units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Units received upon vesting (in shares) | shares								1
Restricted Stock Units (RSU) Deemed not Granted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Awards converted (in shares) | shares			1,900,000
Direct Equity Interest | President and Chief Executive Officer
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Award vesting period				5 years
Direct Equity Interest | President and Chief Executive Officer | Award Based on Service Period
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting percentage				50.00%
Direct Equity Interest | President and Chief Executive Officer | Award Based on Service Period and Achievement of Certain Performance Based Thresholds
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting percentage				50.00%
RSUs
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Compensation cost not yet recognized					$ 7,300,000			$ 7,300,000
Number of unvested phantom units (in shares) | shares					1,100,000			1,100,000
Period for recognition of unrecognized compensation cost								3 years
RSUs | IPO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Performance-based restricted common stock (in shares) | shares		1,700,000
Restricted Stock Units (RSU), Performance Based, Deemed Not Granted | IPO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Performance-based restricted common stock (in shares) | shares		600,000